Topic of the Moment – the International Space Station

After criticism of the International Space Station for being a ‘waste of money’ and the selection of a UK astronaut as a future crewmember, we look at what goes on 240 miles above the Earth.

Credit: NASA

NASA astronaut Commander Chris Hadfield has hit back at suggestions that the International Space Station serves little scientific purpose.

The ISS carries out a great deal of research that relies on its unique status – whether the experiments require microgravity, exposure to the conditions of space, or simply placement above the Earth’s atmosphere.

Meanwhile, UK astronaut Major Tim Peake has been selected to join the ISS crew for five months from December 2015.

Peake, a former British Army helicopter pilot, will be the first UK-born astronaut to join the ISS crew as part of a European Space Agency mission, rather than after taking US citizenship to work with NASA.

Europe had originally planned its own space station, Columbus. In 1993 this merged with the US programme Freedom, aimed at building a permanently inhabited space station, and a planned Russian successor to Mir.

The station’s largest single module was contributed by Japan, and the robotic arms used for assembly and maintenance are Canadian. Crewmembers from these participating nations live and work alongside one another for months at a time.

The research they carry out covers the whole spectrum of life- and physical sciences. And it’s thought of, too, as a testing ground for an eventual return to the Moon and then manned journeys to Mars and perhaps beyond.

New space systems designed for long-distance journeys in the future can be tested in an environment similar to that in which they’ll ultimately be used, while the effects of microgravity on combustion may lead to breakthroughs in propulsion or energy-generation.

The station is investigating the effect of long-duration stays in space on human physiology. Astronauts who’ve remained aboard for a substantial time experience atrophy of the muscles usually used to support posture – since they’re not needed in weightless conditions – and a reduction in bone density. The former can be countered with the exercise machines placed on board, but the loss of bone density that occurs after just a few months in space takes up to three years to recover – which would make manned interplanetary journeys difficult.

The ISS also tests the effects a space environment has on other forms of life as well as on humans. A batch of tardigrades – millimetre-long, eight-legged creatures that usually live in water – survived for 10 days outside the space station despite the lack of oxygen, water or atmospheric pressure and the presence of radiation.

But it’s not just planning for the expansion of space travel or looking at weird creatures: the station is home to cutting-edge fundamental physics research too.

For example the Alpha Magnetic Spectrometer (AMS) is a particle detector designed to investigate antimatter in cosmic rays. Our universe appears to be made entirely of matter, when theory suggests that the Big Bang should have created equal amounts of matter and antimatter. AMS is looking for evidence of antihelium nuclei right up to the edge of the observable universe to try to confirm whether our picture of the cosmos is correct.

It’s also looking for the signature of dark matter – particles that have mass but are very difficult to detect. Its existence was postulated because there seems to be more mass in the universe than is accounted for by phenomena that we can see. Collisions between one possible type of dark matter should produce signals that AMS will be able to pick up.

The detector was installed on the ISS in 2011 and the first results were released in April 2013 – and are believed to be consistent with the annihilation of dark-matter particles in space.

The project attracted criticism from the Astronomer Royal Lord Rees on the grounds of its astronomical cost, however – it overran to around $1.5 bn, which he suggested could have been better spent.

The total cost of ISS itself is around $150 bn, making it possibly the most expensive construction in history. It will remain in operation until at least 2020 – leaving plenty of time for Commander Hadfield’s successors to try to outdo his orbital music video.